The amount they’re paid depends on how many lines they have. An extra is basically the lowest on the totem pole, and if they had a speaking role, they’d get paid more per SAG rules. Thus the production just gives them silent roles so they don’t have to pay as much.
Can I wear jeans to an audition?
You don’t need to dress like you’re going in for a corporate interview here. Your clothes shouldn’t be a wrinkled mess, but you also shouldn’t be wearing business attire to an audition. A good pair of jeans can go a long way, and it’s worth investing in a pair for auditions alone.